Carotenoid ketolase genes and gene products, production of ketocarotenoids and methods of modifying carotenoids using the genes

ABSTRACT

A purified nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has the nucleic acid sequence of SEQ ID NO: 1 or 3, or has a sequence which encodes the amino acid sequence of SEQ ID NO: 2 or 4, as well as vectors and host cells containing them. Methods of use of the nucleic acid sequences to produce ketocarotenoid in host cells and methods of use of the nucleic acid sequences to modify the production of carotenoids in a host cell are included.

This application is a 371 of PCT//US99/10455 filed May. 21, 1999, which claims the benefit of U.S. provisional application No. 60/086,460, filed May 22, 1998.

BACKGROUND OF THE INVENTION

Carotenoids are widely distributed natural pigments that are responsible for many of the yellow, orange and red colors seen in living organisms. They have important commercial uses as coloring agents in the food industry, as feed and food additives, in cosmetics and as provitamin A precursors.

The plant species Adonis aestivalis produces flowers with petals that are deep red in color and nearly black at the base of the petals due to the accumulation of ketocarotenoid and other carotenoid pigments (Neamtu et al., Rev. Roum. Biochim. 6:157, 1969). This pattern of carotenoid accumulation accounts for the common name of some varieties of this species: summer pheasant's eye.

Among the carotenoids identified in the petals of the red petal varieties of these various species is the ketocarotenoid astaxanthin (3,3′-dihydroxy-4,4′-diketo-b,b-carotene; see FIG. 1). Various other ketocarotenoids (see FIG. 1) including 3-hydroxyechinenone (3-hydroxy-4-keto-b,b-carotene),adonirubin (3-hydroxy-4,4′-diketo-b,b-carotene) adonixanthin (3,3′-dihydroxy-4-keto-b,b-carotene) and isozeaxanthin (4,4′-dihydroxy-b,b-carotene; see T. W. Goodwin, The Biochemistry of the Carotenoids, vol I. Plants, 2nd edition, 1980, page 147) have also been reported. The latter compound is consistent with speculation that the 4-hydroxy may be an intermediate in the formation of the 4-keto group.

SUMMARY OF THE INVENTION

There is appreciable interest in the biological production of carotenoids, in particular the orange-colored ketocarotenoids such as astaxanthin and canthaxanthin (FIG. 1), and in the modification of carotenoid composition. For this reason, an A. aestivalis flower cDNA library was constructed and screened for cDNAs encoding enzymes (hereinafter referred to as “ketolases” although the specific biochemical activity has not yet been established) involved in the conversion of b-carotene into orange compounds with absorption properties similar to those exhibited by common ketocarotenoids such as canthaxanthin (FIG. 1). Two distinctly different Adonis aestivalis cDNAs were obtained from among a number of cDNAs that were selected on this basis.

Thus, a first aspect of the present invention is a purified nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has the nucleic acid sequence of SEQ ID NO: 1 or 3.

The invention also includes a purified nucleic acid sequence which encodes for a protein having ketolase enzyme activity and having the amino acid sequence of SEQ ID NO: 2 or 4.

The invention also includes vectors which comprise any portion of the nucleic acid sequences listed above, and host cells transformed with such vectors.

Another aspect of the present invention is a method of producing a ketocarotenoid in a host cell, the method comprising

inserting into the host cell a vector comprising a heterologous nucleic acid sequence which encodes for a protein having ketolase enzyme activity and comprises (1) SEQ ID NO: 1 or 3 or (2) a sequence which encodes the amino acid sequence of SEQ ID NO: 2 or 4, wherein the heterologous nucleic acid sequence is operably linked to a promoter; and

expressing the heterologous nucleic acid sequence, thereby producing the ketolase enzyme.

Another subject of the present invention is a method of modifying the production of carotenoids in a host cell, relative to an untransformed host cell, the method comprising

inserting into a host cell which already produces carotenoids a vector comprising a heterologous nucleic acid sequence which encodes for a protein having ketolase enzyme activity and comprises (1) SEQ ID NO: 1 or 3 or (2) a sequence which encodes the amino acid sequence of SEQ ID NO: 2 or 4, wherein the heterologous nucleic acid sequence is operably linked to a promoter; and

expressing the heterologous nucleic acid sequence in the host cell to modify the production of the carotenoids in the host cell, relative to an untransformed host cell.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

FIG. 1 illustrates structures and biochemical routes leading from b-carotene to various of the ketocarotenoids referred to in the text. Conversion of β-carotene to astaxanthin by a hydroxylase enzyme (Hy) and a ketolase enzyme (keto) could proceed via any one or all of several possible routes depending on the order of the reactions.

FIG. 2 illustrates the beta ring structure of b-carotene and various modifications of this parent ring that might be produced through the action of the products of the A. aestivalis ketolase cDNAs. Also shown is the structure of the epsilon ring, not found to be a substrate for the A. aestivalis ketolases and present in carotenoids such as d-carotene, e-carotene, a-carotene and lutein.

FIG. 3 illustrate results obtained with TLC (thin layer chromatography) separation of carotenoid pigments extracted from E. coli cultures, previously engineered to produce b-carotene, but that now also contain the A. aestivalis ketolase cDNAs and/or other introduced genes and cDNAs. The Figure indicates the empty plasmid vector pBluescript SK- (SK-), the Adonis aestivalis ketolase 1 cDNA in this plasmid vector (Ad keto1), the Haematococcus pluvialis ketolase cDNA in this plasmid vector Hp keto), or the Arabidopsis β-carotene hydroxylase cDNA (At Ohase). Bands that were orange in color are shown here with a darker fill than those with a yellow color. Identities of various bands are indicated to the right of the band.

FIG. 4 illustrates the absorption spectrum of one of the orange carotenoids produced from b-carotene via the action of the Adonis ketolases and makes clear the similarity of the spectrum to that of canthaxanthin. Absorption spectra (in acetone) of β-carotene, canthaxanthin and an unknown orange product (orange band #1; the lower orange band in the first lane of FIG. 3) extracted from cultures after introduction of the Adonis aestivalis keto1 cDNA (SEQ ID NO: 1) in cells of E. coli that otherwise produce and accumulate β-carotene. The absorption spectrum of the unknown resembles that of canthaxanthin but the compound migrates to a position below echinenone on RP18 TLC plates developed with a mobile phase of methanol:acetone (1:1 by volume). The absorption spectrum of orange band #2 also is similar to that of canthaxanthin but it migrates more rapidly than canthaxanthin indicating that it is probably a more polar compound.

FIG. 5 shows SEQ ID NO: 5 (the sequence shown in this Figure includes SEQ ID NO: 1 and also includes some of the flanking DNA from the adapator DNA and the multiple cloning site (MCS) of the library cloning vector, which sequences are shown in bold).

FIG. 6 shows SEQ ID NO: 6 (the sequence shown in this Figure includes SEQ ID NO: 2 and also includes a translation of amino acids resulting from the adapator DNA and the multiple cloning site (MCS) of the library cloning vector and the start codon from the plasmid vector pTrcHis, which sequences are shown in bold and capitalized).

FIG. 7 shows SEQ ID NO: 7 (the sequence shown in this Figure includes SEQ ID NO: 3 and also includes some of the flanking DNA from the adapator DNA and the multiple cloning site (MCS) of the library cloning vector, which sequences are shown in bold).

FIG. 8 shows SEQ ID NO: 8 (the sequence shown in this Figure includes SEQ ID NO: 4 and also includes a translation of amino acids resulting from the adapator DNA and the multiple cloning site (MCS) of the library cloning vector and the start codon from the plasmid vector, which sequences are shown in bold and capitalized).

FIG. 9 shows a “Gap” alignment of the two Adonis ketolase sequences of the invention. A truncated version of SEQ ID NO: 1 is shown in this Figure for comparitive purposes, and is designated SEQ ID NO: 9. The percentage identity was calculated to be 91.107.

FIG. 10 shows a “Gap” alignment of SEQ ID NO: 2 and 4. The following results were found:

Gap weight: 12 average match: 2.912 Length weight: 4 average mismatch: −2.003 Quality: 1440 length: 307 Ratio: 4.691 gaps: 0 percent similarity: 92.182 percent identity: 90.228

FIG. 11 shows a comparison between SEQ ID NO: 2 and the Arabidopsis thaliana β-carotene hydroxylase enzyme (GenBank U58919) (SEQ ID NO: 10).

FIG. 12A shows gDNA (SEQ ID NO: 11) immediately upstream of the cDNA of SEQ ID NO: 3. The sequence was obtained from a PCR product generated using the GenomeWalker kit of Clontech Laboratories, Inc. (1020 East Meadow Circle, Palo Alto, Calif. 94303-4230) and nested primers specific to the ketolases of Adonis aestivalis (cagaatcggtctgttctattagttcttcc (SEQ ID NO: 17) and caatttgaggaatatcaaggttccttgttctc (SEQ ID NO: 18)). The termination codon upstream of and in-frame with initiation codon (TAA at positions 204-206) is shown in bold. Initiation codon (ATG) is also shown in bold.

FIG. 12B (SEQ ID NO: 12) indicates that the full length polypeptide of SEQ ID NO: 4 begins with the amino acids MAA (shown in bold) immediately preceding the ketolase sequence shown in FIG. 8. A similar MAA amino acid sequence immediately preceding SEQ ID NO: 1 is also expected.

FIG. 13 shows an alignment of SEQ ID NO: 2, SEQ ID NO: 12, an Arabidopsis β-carotene hydroxylase enzyme (predicted product of GenBank U58919) (SEQ ID NO: 13), a putative second Arabidopsis hydroxylase predicted by genomic DNA sequence (GenBank AB025606; the exon/intron junctions were chosen with reference to the product of the Arabidopsis β-carotene hydroxylase cDNA u58919) (SEQ ID NO: 14), and two Capsicum annuum β-carotene hydroxylases (predicted products of GenBank Y09722 and Y09225) (SEQ ID NO: 15 and 16).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a purified nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has the nucleic acid sequence of SEQ ID NO: 1 or 3.

The invention also includes a purified nucleic acid sequence which encodes for a protein having ketolase enzyme activity and having the amino acid sequence of SEQ ID NO: 2 or 4.

Two different but closely-related nucleic acids have been isolated. The sequences of the longest example of each are presented herein. Sequencing which has subsequently been conducted of upstream genomic DNA indicates that SEQ ID NO: 3 lacks bases encoding the first three amino acids (MAA; see FIG. 12). Likely, this is also the case for SEQ ID NO: 1, but the upstream genomic sequences have not yet been obtained for this nucleic acid.

The two different Adonis ketolases denoted in SEQ ID NO: 1 and 3 are similar in sequence, sharing about 91% identity, as determined by the Gap program discussed below (see FIG. 9). The predicted amino acid sequences of the enzymes denoted in SEQ ID NO: 2 and 4 share about 92% similarity and about 90% identity, also as determined by the Gap program (see FIG. 10).

Therefore, it is clear that certain modifications of SEQ ID NO: 1 or 3 or SEQ ID NO: 2 or 4 can take place without destroying the activity of the enzyme. Note also that certain truncated versions of the cDNAs of SEQ ID NO: 1 or 3 were found to be functional (i.e., these cDNAs retained the property of causing the conversion of b-carotene to orange compounds). Also, the Arabidopsis β-carotene hydroxylase (GenBank U58919), aligned with the ketolase SEQ ID NO: 2 in FIG. 11, retains catalytic function when truncated to yield a polypeptide that lacks the first 129 amino acids (Sun et al., 1996). From the alignment in FIG. 11, therefore, this would suggest that the two ketolases of the invention retain catalytic activity after truncation to remove bases encoding the first 132 amino acids.

Thus, the present invention is intended to include those ketolase nucleic acid and amino acid sequences in which substitutions, deletions, additions or other modifications have taken place, as compared to SEQ ID NO: 1 or 3 or SEQ ID NO: 2 or 4, without destroying the activity of the ketolase enzyme. Preferably, the substitutions, deletions, additions or other modifications take place at those positions which already show dissimilarity between the present sequences. For SEQ ID NO: 1, as shown in FIG. 9, these positions are as follows: positions 7, 20, 23, 35, 53, 63, 65, 67, 76, 78, 85, 86, 91, 107, 109-111, 135, 140, 144, 146, 160, 168, 217, 219, 241, 249, 254, 256, 271, 291, 296, 349, 389, 400, 406, 431, 448, 449, 460, 471, 499, 530, 589, 619, 643, 653, 654, 667, 679, 709, 731, 742, 784, 787, 836, 871, 883, 896, 911, 919, 928, 930, 939, 943, 967, 969, 978, 979, 982, 988, 995, 1005, 1006, 1012-1014, 1017, 1019-1021, 1023, 1025, 1049, 1050, 1054, 1060-1068, 1070-1073, 1075, 1094, 1100, 1101, 1106, 1107, 1109 and 1111-1176. For SEQ ID NO: 3, as shown in FIG. 9, these positions are as follows: positions 7, 20, 23, 35, 53, 63, 65, 67, 76, 78, 85, 86, 91, 107, 109-111, 135, 140, 144, 146, 160, 168, 217, 219, 241, 249, 254, 256, 271, 291, 296, 349, 389, 400, 406, 431, 448, 449, 460, 471, 499, 530, 589, 619, 643, 653, 654, 667, 679, 709, 731, 742, 784, 787, 836, 871, 883, 896, 911, 919, 928, 930, 939, 943, 966, 967, 970, 979, 980, 983, 989, 996, 1006, 1007, 1013-1015, 1018, 1020-1022, 1024, 1026, 1050, 1051, 1055, 1062-1065, 1067, 1086, 1092, 1093, 1098, 1099, 1101 and 1103-1112.

For SEQ ID NO: 2 and 4, as shown in FIG. 10, the following amino acids can be substituted or deleted, or additions or other modifications can be made, without destroying the activity of the ketolase enzyme: positions 7, 8, 12, 18, 21, 22, 25, 26, 36, 37, 45, 47-49, 56, 73, 83, 85, 97, 99, 130, 144, 150, 157, 166, 218, 244, 279, 299 and 304. Therefore, the present invention also intends to cover amino acid sequences where such changes have been made.

In each case, nucleic acid and amino acid sequence similarity and identity is measured using sequence analysis software, for example, the Sequence Analysis, Gap, or BestFit software packages of the Genetics Computer Group (University of Wis. Biotechnology Center, 1710 University Avenue, Madison, Wis. 53705), MEGAlign (DNAStar, Inc., 1228 S. Park St., Madison, Wis. 53715), or MacVector (Oxford Molecular Group, 2105 S. Bascom Avenue, Suite 200, Campbell, Calif. 95008). Such software uses algorithms to match similar sequences by assigning degrees of identity to various substitutions, deletions, and other modifications, and includes detailed instructions as to useful parameters, etc., such that those of routine skill in the art can easily compare sequence similarities and identities. An example of a useful algorithm in this regard is the algorithm of Needleman and Wunsch, which is used in the Gap program discussed above. This program finds the alignment of two complete sequences that maximizes the number of matches and minimizes the number of gaps. Another useful algorithm is the algorithm of Smith and Waterman, which is used in the BestFit program discussed above. This program creates an optimal alignment of the best segment of similarity between two sequences. Optimal alignments are found by inserting gaps to maximize the number of matches using the local homology algorithm of Smith and Waterman.

Conservative (i.e. similar) substitutions typically include substitutions within the following groups: glycine and alanine; valine, isoleucine and leucine; aspartic acid, glutamic acid, asparagine and glutamine; serine and threonine; lysine and arginine; and phenylalanine and tyrosine. Substitutions may also be made on the basis of conserved hydrophobicity or hydrophilicity (see Kyte and Doolittle, J. Mol. Biol. 157: 105-132 (1982)), or on the basis of the ability to assume similar polypeptide secondary structure (see Chou and Fasman, Adv. Enzymol. 47: 45-148 (1978)).

If comparison is made between nucleotide sequences, preferably the length of comparison sequences is at least 50 nucleotides, more preferably at least 60 nucleotides, at least 75 nucleotides or at least 100 nucleotides. It is most preferred if comparison is made between the nucleic acid sequences encoding the enzyme coding regions necessary for enzyme activity. If comparison is made between amino acid sequences, preferably the length of comparison is at least 20 amino acids, more preferably at least 30 amino acids, at least 40 amino acids or at least 50 amino acids. It is most preferred if comparison is made between the amino acid sequences in the enzyme coding regions necessary for enzyme activity.

While the two different Adonis ketolase enzymes of the present invention are similar in sequence, previously-described bacterial (Misawa et al., 1995), cyanobacterial (Fernandez-Gonzalez et al.,1997), and green algal (Haematococcus pluvialis; Lotan et al., 1995; Kajiwara et al., 1995) β-carotene ketolase enzymes bear little resemblance to the Adonis ketolases, although certain histidine motifs and features of the predicted secondary structure are common to the polypeptides predicted by both groups (Cunningham and Gantt, 1998).

The present invention also includes vectors containing the nucleic acids of the invention. Suitable vectors according to the present invention comprise a gene encoding a ketolase enzyme as described above, wherein the gene is operably linked to a suitable promoter. Suitable promoters for the vector can be constructed using techniques well known in the art (see, for example, Sambrook et al., Molecular Cloning A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y., 1989; Ausubel et al., Current Protocols in Molecular Biology, Greene Publishing and Wiley Interscience, New York, 1991). Suitable vectors for eukaryotic expression in plants are described in Fray et al., (1995; Plant J. 8:693-701) and Misawa et al, (1994; Plant J. 6:481-489). Suitable vectors for prokaryotic expression include pACYC184, pUC119, and pBR322 (available from New England BioLabs, Bevery, Mass.) and pTrcHis (Invitrogen) and pET28 (Novagen) and derivatives thereof. The vectors of the present invention can additionally contain regulatory elements such as promoters, repressors, selectable markers such as antibiotic resistance genes, etc., the construction of which is very well known in the art.

The genes encoding the ketolase enzymes as described above, when cloned into a suitable expression vector, can be used to overexpress these enzymes in a host cell expression system or to inhibit the expression of these enzymes. For example, a vector containing a gene of the invention may be used to increase the amount of ketocarotenoids in an organism and thereby alter the nutritional or commercial value or pharmacology of the organism. A vector containing a gene of the invention may also be used to modify the carotenoid production in an organism.

Therefore, the present invention includes a method of producing a ketocarotenoid in a host cell, the method comprising

inserting into the host cell a vector comprising a heterologous nucleic acid sequence which encodes for a protein having ketolase enzyme activity and comprises (1) SEQ ID NO: 1 or 3 or (2) a sequence which encodes the amino acid sequence of SEQ ID NO: 2 or 4, wherein the heterologous nucleic acid sequence is operably linked to a promoter; and

expressing the heterologous nucleic acid sequence, thereby producing the ketocarotenoid.

The present invention also includes a method of modifying the production of carotenoids in a host cell, relative to an untransformed host cell, the method comprising

inserting into a host cell which already produces carotenoids a vector comprising a heterologous nucleic acid sequence which encodes for a protein having ketolase enzyme activity and comprises (1) SEQ ID NO: 1 or 3 or (2) a sequence which encodes the amino acid sequence of SEQ ID NO: 2 or 4, wherein the heterologous nucleic acid sequence is operably linked to a promoter; and

expressing the heterologous nucleic acid sequence in the host cell to modify the production of the carotenoids in the host cell, relative to an untransformed host cell.

The term “modifying the production” means that the amount of carotenoids produced can be enhanced, reduced, or left the same, as compared to an untransformed host cell. In accordance with one embodiment of the present invention, the make-up of the carotenoids (i.e., the type of carotenoids produced) is changed vis a vis each other, and this change in make-up may result in either a net gain, net loss, or no net change in the amount of carotenoids produced in the cell. In accordance with another embodiment of the present invention, the production or the biochemical activity of the carotenoids (or the enzymes which catalyze their formation) is enhanced by the insertion of the ketolase enzyme-encoding nucleic acid. In yet another embodiment of the invention, the production or the biochemical activity of the carotenoids (or the enzymes which catalyze their formation) may be reduced or inhibited by a number of different approaches available to those skilled in the art, including but not limited to such methodologies or approaches as anti-sense (e.g., Gray et al. (1992), Plant Mol. Biol. 19:69-87), ribozymes (e.g., Wegener et al (1994) Mol. Gen. Genet. Nov. 15, 1994; 245(4):465-470), co-suppression (e.g. Fray et al. (1993) Plant Mol. Biol. 22:589-602), targeted disruption of the gene (e.g., Schaefer et al. Plant J. 11:1195-1206, 1997), intracellular antibodies (e.g., see Rondon et al. (1 997) Annu. Rev. Microbiol. 51:257-283) or whatever other approaches rely on the knowledge or availability of the nucleic acid sequences of the invention, or the enzymes encoded thereby.

Host systems according to the present invention preferably comprise any organism which is capable of producing carotenoids, or which already produces carotenoids. Such organisms include plants, algae, certain bacteria, cyanobacteria and other photosynthetic bacteria. Transformation of these hosts with vectors according to the present invention can be done using standard techniques. See, for example, Sambrook et al., Molecular Cloning A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y., 1989; Ausubel et al., Current Protocols in Molecular Biology, Greene Publishing and Wiley Interscience, New York, 1991.

Alternatively, transgenic organisms can be constructed which include the nucleic acid sequences of the present invention. The incorporation of these sequences can allow the controlling of carotenoid biosynthesis, content, or composition in the host cell. These transgenic systems can be constructed to incorporate sequences which allow for the overexpression of the various nucleic acid sequences of the present invention. Transgenic systems can also be constructed which allow for the underexpression of the various nucleic acid sequences of the present invention. Such systems may contain anti-sense expression of the nucleic acid sequences of the present invention. Such anti-sense expression would result in the accumulation of the substrates of the enzyme encoded by the sense strand.

Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.

EXAMPLE 1 Isolation of Plant cDNAs that Convert b-Carotene into Compounds with Ketocarotenoid-like Spectra

A flower cDNA library from the plant Adonis aestivalis was introduced into a strain of Escherichia coli engineered to accumulate the yellow carotenoid pigment β-carotene (see Cunningham et al., Plant Cell 8:1613-26, 1996). This strain of E. coli normally forms yellow colonies when cultures are spread on a solid agar growth medium. Ketocarotenoids that are derived from b-carotene, such as echinenone and canthaxanthin (FIG. 1), are, in contrast, orange to orange-red in color. Colonies that were orange rather than yellow in color were visually selected, and the DNA sequences of the Adonis aestivalis cDNAs within the plasmid vectors contained in these colonies were ascertained. Two distinct cDNAs were obtained from analysis of cDNA inserts in plasmids obtained from approximately 10 selected colonies. The DNA sequences of these two ketolase cDNAs are presented herein.

The products produced by the ketolases of the invention which have been expressed in a β-carotene-accumulating strain of Eschericia coli have not yet been identified. As many as 5 or 6 different colored bands, in addition to the substrate β-carotene, may readily be discerned by C₁₈ TLC separation (see FIG. 3). To provide appropriate standards to assist in identification, an H. pluvialis ketolase and an Arabidopsis β-carotene hydroxylase were separately introduced into the β-carotene-accumulating E. coli to produce echinenone (3-keto-β,β-carotene) and canthaxanthin (3,3′-diketo-β,β-carotene) or β-cryptoxanthin (4-hydroxy-β,β-carotene) and zeaxanthin (4,4′-dihydroxy-β,β-carotene). None of the compounds formed in the presence of the ketolases of the invention (no difference was observed in products formed in the presence of the two different nucleic acid sequences of the invention) both migrate in the TLC system and have the absorption spectrum expected for echinenone, canthaxanthin, β-cryptoxanthin, or zeaxanthin. Two of the colored TLC bands produced in the presence of the Adonis ketolase cDNAs are orange in color. Orange band #1 has an absorption spectrum similar to that of canthaxanthin (see FIG. 4) but migrates in a position that indicates a polarity intermediate to echinenone and β-carotene. Orange band #2 also has an absorption spectrum like that of canthaxanthin but migrates in a position that indicates a polarity intermediate to canthaxanthin and zeaxanthin (see FIG. 3). The absorption spectra and TLC results suggest that the two orange products could be desaturated at the 3-4 positions of both rings (3,4,-didehydro; see FIG. 2). Orange band #1 (see FIG. 3) might then be 3,4,3′,4′-tetradehydro-β,β-carotene. To substantially affect the absorption spectrum of the substrate β-carotene, any modifications very likely involve a carbon that lies in conjugation with the conjugated chain of carbon-carbon double bonds that constitute the chromophore (Goodwin, 1980; The Biochemistry of the Carotenoids, volume I; 2^(nd) edition, Chapman and Hall). For the spectra obtained, only the carbons at the number 4 position of the two rings appear to be plausible locations for modification. The multitude and TLC migrations of the yellow and orange products produced from the symmetrical β-carotene, however, also indicates that the enzymes of the invention carry out more than a single type of reaction. The apparent homology of the ketolases of the invention to the Arabidopsis β-carotene hydroxylase would suggest that compounds with a hydroxyl at the 3 and/or 4 positions of one or both rings are another possible outcome (see FIG. 2). In fact, such compounds have been identified in Adonis (see above), and it has long been conjectured that a hydroxyl at position 4 is an intermediate in the formation of the 4-keto (e.g. crustaxanthin, a 3,3′,4,4′ tetrahydroxy carotenoid that might be a precursor for astaxanthin in the exoskeleton of the lobster). The histidine motifs and secondary structure in common to the hydroxylase and ketolase enzymes are characteristics of a large group of di-iron oxygenases whose members also include examples of desaturases (J. Shanklin, 1998, Ann. Rev. Plant Physiol. Plant Mol. Biol.), therefore a 3-4 desaturation (and/or perhaps a 2-3 desaturation in one or more of the yellow compounds) would also seem a plausible outcome.

To summarize the results of this example for the Adonis ketolases of the invention, a number of different carotenoids, including two with ketocarotenoid-like spectra, are produced from β-carotene via the action of the products of either of the two different nucleic acids of the invention. These orange compounds appear to be the major products. Truncation and fusion of the cDNAs to a stronger promoter in the vector pTrcHis (Invitrogen) was detrimental to growth of E. coli but did result in improved yield of the most polar orange product (orange band #2 in FIG. 3). Introduction of a cyanobacterial ferredoxin did not change the yield or relative amounts of the various products. Without being bound by theory, it may be that the ketocarotenoids produced in flower petals of Adonis actually include the as yet unidentified orange compounds that are produced in E. coli using the nucleic acids of the invention.

EXAMPLE 2 Substrate Specificity of the Adonis Ketolases

Carotenoids with ε rings are common in plants. The ε ring differs from the b ring only in the position of the double bond within the ring (FIG. 2). The ε ring is reported to be a poor substrate for the Arabidopsis b-carotene hydroxylase (Sun et al., 1996). The Adonis ketolase cDNAs were introduced into strains of E. coli engineered (Cunningham et al., 1996) to accumulate carotenoids with one or two ε rings (d-carotene and ε-carotene), or the acyclic carotenoid lycopene. TLC analysis of acetone extracts revealed that these carotenoids were not modified by the Adonis ketolases. as indicated by a lack of any new products formed. Products produced in E. coli engineered to accumulate zeaxanthin (Sun et al., 1996) appeared to be the same as for β-carotene accumulating cultures indicating that a 3-OH is likely to be one of the functional groups introduced to the b ring by the Adonis ketolases. The more polar orange band produced from b-carotene through the action of the Adonis ketolases (e.g., orange band 2 in FIG. 3), therefore, could very well be 3,3′-dihydroxy-3,4,3′,4′-tetradehydro-b,b-carotene.

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18 1 1176 DNA Adonis aestivalis 1 agcaatctca gtgttcagta caagttattc tttccacaag aatctcttgt tgcactcaaa 60 acaagacatt ctcaaccgcc catgtttgct cttctctcca gttgtggtgg agtcgcctat 120 gagaaagaaa aagacacatc gtgctgcatg tatctgctct gttgcagaga gaacaaggaa 180 ccttgatatt cctcaaattg aagaagagga agagaacgag gaagaactaa tagaacagac 240 ggattctggc ataattcata taaagaaaac gctagggggg aaacaatcaa gacggtccac 300 tggctccatt gtcgcacccg tatcttgtct tgggatcctt tcaatgatcg gacctgctgt 360 ttacttcaag ttttcacggc taatggagtg tggagatatt cctgtcgcag aaatggggat 420 tacgtttgcc gcctttgttg ctgctgcgat tggcacggaa tttttgtcag gatgggttca 480 caaagaactc tggcacgatt ctttgtggta cattcacaag tctcaccata ggtcacgaaa 540 aggccgcttc gagttcaatg atgtgtttgc tattattaac gcgcttcctg ctattgctct 600 tatcaattat ggattctcaa atgaaggcct ccttcctgga gcctgctttg gtaccggtct 660 tggaacgaca gtctgtggca tggcttacat ttttcttcac aatggccttt cacaccgaag 720 gttcccagta gggcttattg caaacgtccc ttatttccac aagctggctg cagctcacca 780 aatccatcac tcaggaaaat ttcagggtgt accatttggc ctgttccttg gaccccagga 840 attggaagaa gtaagaggag gcactgaaga attggagagg gtgatcagtc gtacagctaa 900 acgaacgcaa tcatctacat gaatcaactc ttttacattt atgaggtttt agtttatcgg 960 tgttacaagt cacacatttg tgtcgttgta gtaattcaaa gttaccatac tcttttttag 1020 aatttttttt tgatgtatag gtcgcggagt tacggttaca aaggccaaat ctattgttgt 1080 ggaattccat tattaaaaat aaaaattaga gtttgtagtt ttatctggtg atcaatatca 1140 atatatatta attaaagcaa aaaaaaaaaa aaaaaa 1176 2 306 PRT Adonis aestivalis 2 Ala Ile Ser Val Phe Ser Thr Ser Tyr Ser Phe His Lys Asn Leu Leu 1 5 10 15 Leu His Ser Lys Gln Asp Ile Leu Asn Arg Pro Cys Leu Leu Phe Ser 20 25 30 Pro Val Val Val Glu Ser Pro Met Arg Lys Lys Lys Thr His Arg Ala 35 40 45 Ala Cys Ile Cys Ser Val Ala Glu Arg Thr Arg Asn Leu Asp Ile Pro 50 55 60 Gln Ile Glu Glu Glu Glu Glu Asn Glu Glu Glu Leu Ile Glu Gln Thr 65 70 75 80 Asp Ser Gly Ile Ile His Ile Lys Lys Thr Leu Gly Gly Lys Gln Ser 85 90 95 Arg Arg Ser Thr Gly Ser Ile Val Ala Pro Val Ser Cys Leu Gly Ile 100 105 110 Leu Ser Met Ile Gly Pro Ala Val Tyr Phe Lys Phe Ser Arg Leu Met 115 120 125 Glu Cys Gly Asp Ile Pro Val Ala Glu Met Gly Ile Thr Phe Ala Ala 130 135 140 Phe Val Ala Ala Ala Ile Gly Thr Glu Phe Leu Ser Gly Trp Val His 145 150 155 160 Lys Glu Leu Trp His Asp Ser Leu Trp Tyr Ile His Lys Ser His His 165 170 175 Arg Ser Arg Lys Gly Arg Phe Glu Phe Asn Asp Val Phe Ala Ile Ile 180 185 190 Asn Ala Leu Pro Ala Ile Ala Leu Ile Asn Tyr Gly Phe Ser Asn Glu 195 200 205 Gly Leu Leu Pro Gly Ala Cys Phe Gly Thr Gly Leu Gly Thr Thr Val 210 215 220 Cys Gly Met Ala Tyr Ile Phe Leu His Asn Gly Leu Ser His Arg Arg 225 230 235 240 Phe Pro Val Gly Leu Ile Ala Asn Val Pro Tyr Phe His Lys Leu Ala 245 250 255 Ala Ala His Gln Ile His His Ser Gly Lys Phe Gln Gly Val Pro Phe 260 265 270 Gly Leu Phe Leu Gly Pro Gln Glu Leu Glu Glu Val Arg Gly Gly Thr 275 280 285 Glu Glu Leu Glu Arg Val Ile Ser Arg Thr Ala Lys Arg Thr Gln Ser 290 295 300 Ser Thr 305 3 1112 DNA Adonis aestivalis 3 agcaatttca gtgttcagtt caggttattc tttctacaag aatctcttgt tggactcaaa 60 accaaatatt ctcaaacccc catgcctgct attctctcca gttgtgatca tgtcgcctat 120 gagaaagaaa aagaaacatg gtgatccatg tatctgctcc gttgcaggga gaacaaggaa 180 ccttgatatt cctcaaattg aagaagagga agagaatgtg gaagaactaa tagaacagac 240 cgattctgac atagtgcata taaagaaaac actagggggg aaacaatcaa aacggcccac 300 tggctccatt gtcgcacccg tatcttgtct tgggatcctt tcaatgattg gacctgctgt 360 ttacttcaag ttttcacggc taatggaggg tggagatata cctgtagcag aaatggggat 420 tacgtttgcc acctttgttg ctgctgctgt tggcacggag tttttgtcag catgggttca 480 caaagaactc tggcacgagt ctttgtggta cattcacaag tctcaccatc ggtcacgaaa 540 aggccgcttc gagttcaatg atgtgtttgc tattattaac gcgcttcccg ctattgctct 600 tatcaattat ggattctcca atgaaggcct ccttcctgga gcgtgctttg gtgtcggtct 660 tggaacaaca gtctgtggta tggcttacat ttttcttcac aatggcctat cacaccgaag 720 gttcccagta tggcttattg cgaacgtccc ttatttccac aagctggctg cagctcacca 780 aatacaccac tcaggaaaat ttcagggtgt accatttggc ctgttccttg gacccaagga 840 attggaagaa gtaagaggag gcactgaaga gttggagagg gtaatcagtc gtacaactaa 900 acgaacgcaa ccatctacct gaatcaattt ttttacatat ataaggtttt agtttatcgg 960 tgttataaaa tcacacatcc gtatcgtttt agtaagtcaa agttaagata cttccttctt 1020 agaatatttt ttgatgtata ggtcgcggat atactgttac actattcgtt gtggaattcc 1080 attataaaaa aataaaaaaa aaaaaaaaaa aa 1112 4 306 PRT Adonis aestivalis 4 Ala Ile Ser Val Phe Ser Ser Gly Tyr Ser Phe Tyr Lys Asn Leu Leu 1 5 10 15 Leu Asp Ser Lys Pro Asn Ile Leu Lys Pro Pro Cys Leu Leu Phe Ser 20 25 30 Pro Val Val Ile Met Ser Pro Met Arg Lys Lys Lys Lys His Gly Asp 35 40 45 Pro Cys Ile Cys Ser Val Ala Gly Arg Thr Arg Asn Leu Asp Ile Pro 50 55 60 Gln Ile Glu Glu Glu Glu Glu Asn Val Glu Glu Leu Ile Glu Gln Thr 65 70 75 80 Asp Ser Asp Ile Val His Ile Lys Lys Thr Leu Gly Gly Lys Gln Ser 85 90 95 Lys Arg Pro Thr Gly Ser Ile Val Ala Pro Val Ser Cys Leu Gly Ile 100 105 110 Leu Ser Met Ile Gly Pro Ala Val Tyr Phe Lys Phe Ser Arg Leu Met 115 120 125 Glu Gly Gly Asp Ile Pro Val Ala Glu Met Gly Ile Thr Phe Ala Thr 130 135 140 Phe Val Ala Ala Ala Val Gly Thr Glu Phe Leu Ser Ala Trp Val His 145 150 155 160 Lys Glu Leu Trp His Glu Ser Leu Trp Tyr Ile His Lys Ser His His 165 170 175 Arg Ser Arg Lys Gly Arg Phe Glu Phe Asn Asp Val Phe Ala Ile Ile 180 185 190 Asn Ala Leu Pro Ala Ile Ala Leu Ile Asn Tyr Gly Phe Ser Asn Glu 195 200 205 Gly Leu Leu Pro Gly Ala Cys Phe Gly Val Gly Leu Gly Thr Thr Val 210 215 220 Cys Gly Met Ala Tyr Ile Phe Leu His Asn Gly Leu Ser His Arg Arg 225 230 235 240 Phe Pro Val Trp Leu Ile Ala Asn Val Pro Tyr Phe His Lys Leu Ala 245 250 255 Ala Ala His Gln Ile His His Ser Gly Lys Phe Gln Gly Val Pro Phe 260 265 270 Gly Leu Phe Leu Gly Pro Lys Glu Leu Glu Glu Val Arg Gly Gly Thr 275 280 285 Glu Glu Leu Glu Arg Val Ile Ser Arg Thr Thr Lys Arg Thr Gln Pro 290 295 300 Ser Thr 305 5 1205 DNA Adonis aestivalis 5 gggctgcagg aattcggcac gagagcaatc tcagtgttca gtacaagtta ttctttccac 60 aagaatctct tgttgcactc aaaacaagac attctcaacc gcccatgttt gctcttctct 120 ccagttgtgg tggagtcgcc tatgagaaag aaaaagacac atcgtgctgc atgtatctgc 180 tctgttgcag agagaacaag gaaccttgat attcctcaaa ttgaagaaga ggaagagaac 240 gaggaagaac taatagaaca gacggattct ggcataattc atataaagaa aacgctaggg 300 gggaaacaat caagacggtc cactggctcc attgtcgcac ccgtatcttg tcttgggatc 360 ctttcaatga tcggacctgc tgtttacttc aagttttcac ggctaatgga gtgtggagat 420 attcctgtcg cagaaatggg gattacgttt gccgcctttg ttgctgctgc gattggcacg 480 gaatttttgt caggatgggt tcacaaagaa ctctggcacg attctttgtg gtacattcac 540 aagtctcacc ataggtcacg aaaaggccgc ttcgagttca atgatgtgtt tgctattatt 600 aacgcgcttc ctgctattgc tcttatcaat tatggattct caaatgaagg cctccttcct 660 ggagcctgct ttggtaccgg tcttggaacg acagtctgtg gcatggctta catttttctt 720 cacaatggcc tttcacaccg aaggttccca gtagggctta ttgcaaacgt cccttatttc 780 cacaagctgg ctgcagctca ccaaatccat cactcaggaa aatttcaggg tgtaccattt 840 ggcctgttcc ttggacccca ggaattggaa gaagtaagag gaggcactga agaattggag 900 agggtgatca gtcgtacagc taaacgaacg caatcatcta catgaatcaa ctcttttaca 960 tttatgaggt tttagtttat cggtgttaca agtcacacat ttgtgtcgtt gtagtaattc 1020 aaagttacca tactcttttt tagaattttt ttttgatgta taggtcgcgg agttacggtt 1080 acaaaggcca aatctattgt tgtggaattc cattattaaa aataaaaatt agagtttgta 1140 gttttatctg gtgatcaata tcaatatata ttaattaaag caaaaaaaaa aaaaaaaaac 1200 tcgag 1205 6 315 PRT Adonis aestivalis 6 Met Gly Leu Gln Glu Phe Gly Thr Arg Ala Ile Ser Val Phe Ser Thr 1 5 10 15 Ser Tyr Ser Phe His Lys Asn Leu Leu Leu His Ser Lys Gln Asp Ile 20 25 30 Leu Asn Arg Pro Cys Leu Leu Phe Ser Pro Val Val Val Glu Ser Pro 35 40 45 Met Arg Lys Lys Lys Thr His Arg Ala Ala Cys Ile Cys Ser Val Ala 50 55 60 Glu Arg Thr Arg Asn Leu Asp Ile Pro Gln Ile Glu Glu Glu Glu Glu 65 70 75 80 Asn Glu Glu Glu Leu Ile Glu Gln Thr Asp Ser Gly Ile Ile His Ile 85 90 95 Lys Lys Thr Leu Gly Gly Lys Gln Ser Arg Arg Ser Thr Gly Ser Ile 100 105 110 Val Ala Pro Val Ser Cys Leu Gly Ile Leu Ser Met Ile Gly Pro Ala 115 120 125 Val Tyr Phe Lys Phe Ser Arg Leu Met Glu Cys Gly Asp Ile Pro Val 130 135 140 Ala Glu Met Gly Ile Thr Phe Ala Ala Phe Val Ala Ala Ala Ile Gly 145 150 155 160 Thr Glu Phe Leu Ser Gly Trp Val His Lys Glu Leu Trp His Asp Ser 165 170 175 Leu Trp Tyr Ile His Lys Ser His His Arg Ser Arg Lys Gly Arg Phe 180 185 190 Glu Phe Asn Asp Val Phe Ala Ile Ile Asn Ala Leu Pro Ala Ile Ala 195 200 205 Leu Ile Asn Tyr Gly Phe Ser Asn Glu Gly Leu Leu Pro Gly Ala Cys 210 215 220 Phe Gly Thr Gly Leu Gly Thr Thr Val Cys Gly Met Ala Tyr Ile Phe 225 230 235 240 Leu His Asn Gly Leu Ser His Arg Arg Phe Pro Val Gly Leu Ile Ala 245 250 255 Asn Val Pro Tyr Phe His Lys Leu Ala Ala Ala His Gln Ile His His 260 265 270 Ser Gly Lys Phe Gln Gly Val Pro Phe Gly Leu Phe Leu Gly Pro Gln 275 280 285 Glu Leu Glu Glu Val Arg Gly Gly Thr Glu Glu Leu Glu Arg Val Ile 290 295 300 Ser Arg Thr Ala Lys Arg Thr Gln Ser Ser Thr 305 310 315 7 1141 DNA Adonis aestivalis 7 gggctgcagg aattcggcac gagagcaatt tcagtgttca gttcaggtta ttctttctac 60 aagaatctct tgttggactc aaaaccaaat attctcaaac ccccatgcct gctattctct 120 ccagttgtga tcatgtcgcc tatgagaaag aaaaagaaac atggtgatcc atgtatctgc 180 tccgttgcag ggagaacaag gaaccttgat attcctcaaa ttgaagaaga ggaagagaat 240 gtggaagaac taatagaaca gaccgattct gacatagtgc atataaagaa aacactaggg 300 gggaaacaat caaaacggcc cactggctcc attgtcgcac ccgtatcttg tcttgggatc 360 ctttcaatga ttggacctgc tgtttacttc aagttttcac ggctaatgga gggtggagat 420 atacctgtag cagaaatggg gattacgttt gccacctttg ttgctgctgc tgttggcacg 480 gagtttttgt cagcatgggt tcacaaagaa ctctggcacg agtctttgtg gtacattcac 540 aagtctcacc atcggtcacg aaaaggccgc ttcgagttca atgatgtgtt tgctattatt 600 aacgcgcttc ccgctattgc tcttatcaat tatggattct ccaatgaagg cctccttcct 660 ggagcgtgct ttggtgtcgg tcttggaaca acagtctgtg gtatggctta catttttctt 720 cacaatggcc tatcacaccg aaggttccca gtatggctta ttgcgaacgt cccttatttc 780 cacaagctgg ctgcagctca ccaaatacac cactcaggaa aatttcaggg tgtaccattt 840 ggcctgttcc ttggacccaa ggaattggaa gaagtaagag gaggcactga agagttggag 900 agggtaatca gtcgtacaac taaacgaacg caaccatcta cctgaatcaa tttttttaca 960 tatataaggt tttagtttat cggtgttata aaatcacaca tccgtatcgt tttagtaagt 1020 caaagttaag atacttcctt cttagaatat tttttgatgt ataggtcgcg gatatactgt 1080 tacactattc gttgtggaat tccattataa aaaaataaaa aaaaaaaaaa aaaaactcga 1140 g 1141 8 315 PRT Adonis aestivalis 8 Met Gly Leu Gln Glu Phe Gly Thr Arg Ala Ile Ser Val Phe Ser Ser 1 5 10 15 Gly Tyr Ser Phe Tyr Lys Asn Leu Leu Leu Asp Ser Lys Pro Asn Ile 20 25 30 Leu Lys Pro Pro Cys Leu Leu Phe Ser Pro Val Val Ile Met Ser Pro 35 40 45 Met Arg Lys Lys Lys Lys His Gly Asp Pro Cys Ile Cys Ser Val Ala 50 55 60 Gly Arg Thr Arg Asn Leu Asp Ile Pro Gln Ile Glu Glu Glu Glu Glu 65 70 75 80 Asn Val Glu Glu Leu Ile Glu Gln Thr Asp Ser Asp Ile Val His Ile 85 90 95 Lys Lys Thr Leu Gly Gly Lys Gln Ser Lys Arg Pro Thr Gly Ser Ile 100 105 110 Val Ala Pro Val Ser Cys Leu Gly Ile Leu Ser Met Ile Gly Pro Ala 115 120 125 Val Tyr Phe Lys Phe Ser Arg Leu Met Glu Gly Gly Asp Ile Pro Val 130 135 140 Ala Glu Met Gly Ile Thr Phe Ala Thr Phe Val Ala Ala Ala Val Gly 145 150 155 160 Thr Glu Phe Leu Ser Ala Trp Val His Lys Glu Leu Trp His Glu Ser 165 170 175 Leu Trp Tyr Ile His Lys Ser His His Arg Ser Arg Lys Gly Arg Phe 180 185 190 Glu Phe Asn Asp Val Phe Ala Ile Ile Asn Ala Leu Pro Ala Ile Ala 195 200 205 Leu Ile Asn Tyr Gly Phe Ser Asn Glu Gly Leu Leu Pro Gly Ala Cys 210 215 220 Phe Gly Val Gly Leu Gly Thr Thr Val Cys Gly Met Ala Tyr Ile Phe 225 230 235 240 Leu His Asn Gly Leu Ser His Arg Arg Phe Pro Val Trp Leu Ile Ala 245 250 255 Asn Val Pro Tyr Phe His Lys Leu Ala Ala Ala His Gln Ile His His 260 265 270 Ser Gly Lys Phe Gln Gly Val Pro Phe Gly Leu Phe Leu Gly Pro Lys 275 280 285 Glu Leu Glu Glu Val Arg Gly Gly Thr Glu Glu Leu Glu Arg Val Ile 290 295 300 Ser Arg Thr Thr Lys Arg Thr Gln Pro Ser Thr 305 310 315 9 1149 DNA Adonis aestivalis 9 agcaatctca gtgttcagta caagttattc tttccacaag aatctcttgt tgcactcaaa 60 acaagacatt ctcaaccgcc catgtttgct cttctctcca gttgtggtgg agtcgcctat 120 gagaaagaaa aagacacatc gtgctgcatg tatctgctct gttgcagaga gaacaaggaa 180 ccttgatatt cctcaaattg aagaagagga agagaacgag gaagaactaa tagaacagac 240 ggattctggc ataattcata taaagaaaac gctagggggg aaacaatcaa gacggtccac 300 tggctccatt gtcgcacccg tatcttgtct tgggatcctt tcaatgatcg gacctgctgt 360 ttacttcaag ttttcacggc taatggagtg tggagatatt cctgtcgcag aaatggggat 420 tacgtttgcc gcctttgttg ctgctgcgat tggcacggaa tttttgtcag gatgggttca 480 caaagaactc tggcacgatt ctttgtggta cattcacaag tctcaccata ggtcacgaaa 540 aggccgcttc gagttcaatg atgtgtttgc tattattaac gcgcttcctg ctattgctct 600 tatcaattat ggattctcaa atgaaggcct ccttcctgga gcctgctttg gtaccggtct 660 tggaacgaca gtctgtggca tggcttacat ttttcttcac aatggccttt cacaccgaag 720 gttcccagta gggcttattg caaacgtccc ttatttccac aagctggctg cagctcacca 780 aatccatcac tcaggaaaat ttcagggtgt accatttggc ctgttccttg gaccccagga 840 attggaagaa gtaagaggag gcactgaaga attggagagg gtgatcagtc gtacagctaa 900 acgaacgcaa tcatctacat gaatcaactc ttttacattt atgaggtttt agtttatcgg 960 tgttacaagt cacacatttg tgtcgttgta gtaattcaaa gttaccatac tcttttttag 1020 aatttttttt tgatgtatag gtcgcggagt tacggttaca aaggccaaat ctattgttgt 1080 ggaattccat tattaaaaat aaaaattaga gtttgtagtt ttatctggtg atcaatatca 1140 atatatatt 1149 10 310 PRT Arabidopsis misc_feature (4)..(4) “Xaa” is any amino acid 10 Met Ala Ala Xaa Leu Ser Thr Ala Val Thr Phe Lys Pro Leu His Arg 1 5 10 15 Ser Phe Ser Ser Ser Ser Thr Asp Phe Arg Leu Arg Leu Pro Lys Ser 20 25 30 Leu Ser Gly Phe Ser Pro Ser Leu Arg Phe Lys Arg Phe Ser Val Cys 35 40 45 Tyr Val Val Glu Glu Arg Arg Gln Asn Ser Pro Ile Glu Asn Asp Glu 50 55 60 Arg Pro Glu Ser Thr Ser Ser Thr Asn Ala Ile Asp Ala Glu Tyr Leu 65 70 75 80 Ala Leu Arg Leu Ala Glu Lys Leu Glu Arg Lys Lys Ser Glu Arg Ser 85 90 95 Thr Tyr Leu Ile Ala Ala Met Leu Ser Ser Phe Gly Ile Thr Ser Met 100 105 110 Ala Val Met Ala Val Tyr Tyr Arg Phe Ser Trp Gln Met Glu Gly Gly 115 120 125 Glu Ile Ser Met Leu Glu Met Phe Gly Thr Phe Ala Leu Ser Val Gly 130 135 140 Ala Ala Val Gly Met Glu Phe Trp Ala Arg Trp Ala His Arg Ala Leu 145 150 155 160 Trp His Ala Ser Leu Trp Asn Met His Glu Ser His His Lys Pro Arg 165 170 175 Glu Gly Pro Phe Glu Leu Asn Asp Val Phe Ala Ile Val Asn Ala Gly 180 185 190 Pro Ala Ile Gly Leu Leu Ser Tyr Gly Phe Phe Asn Lys Gly Leu Val 195 200 205 Pro Gly Leu Cys Phe Gly Ala Gly Leu Gly Ile Thr Val Phe Gly Ile 210 215 220 Ala Tyr Met Phe Val His Asp Gly Leu Val His Lys Arg Phe Pro Val 225 230 235 240 Gly Pro Ile Ala Asp Val Pro Tyr Leu Arg Lys Val Ala Ala Ala His 245 250 255 Gln Leu His His Thr Asp Lys Phe Asn Gly Val Pro Tyr Gly Leu Phe 260 265 270 Leu Gly Pro Lys Glu Leu Glu Glu Val Gly Gly Asn Glu Glu Leu Asp 275 280 285 Lys Glu Ile Ser Arg Arg Ile Lys Ser Tyr Lys Lys Ala Ser Gly Ser 290 295 300 Gly Ser Ser Ser Ser Ser 305 310 11 60 DNA Adonis aestivalis 11 cataccataa atagtagagg acaacctaca aaccaaccac cagaaacctc caatggcagc 60 12 309 PRT Adonis aestivalis 12 Met Ala Ala Ala Ile Ser Val Phe Ser Ser Gly Tyr Ser Phe Tyr Lys 1 5 10 15 Asn Leu Leu Leu Asp Ser Lys Pro Asn Ile Leu Lys Pro Pro Cys Leu 20 25 30 Leu Phe Ser Pro Val Val Ile Met Ser Pro Met Arg Lys Lys Lys Lys 35 40 45 His Gly Asp Pro Cys Ile Cys Ser Val Ala Gly Arg Thr Arg Asn Leu 50 55 60 Asp Ile Pro Gln Ile Glu Glu Glu Glu Glu Asn Val Glu Glu Leu Ile 65 70 75 80 Glu Gln Thr Asp Ser Asp Ile Val His Ile Lys Lys Thr Leu Gly Gly 85 90 95 Lys Gln Ser Lys Arg Pro Thr Gly Ser Ile Val Ala Pro Val Ser Cys 100 105 110 Leu Gly Ile Leu Ser Met Ile Gly Pro Ala Val Tyr Phe Lys Phe Ser 115 120 125 Arg Leu Met Glu Gly Gly Asp Ile Pro Val Ala Glu Met Gly Ile Thr 130 135 140 Phe Ala Thr Phe Val Ala Ala Ala Val Gly Thr Glu Phe Leu Ser Ala 145 150 155 160 Trp Val His Lys Glu Leu Trp His Glu Ser Leu Trp Tyr Ile His Lys 165 170 175 Ser His His Arg Ser Arg Lys Gly Arg Phe Glu Phe Asn Asp Val Phe 180 185 190 Ala Ile Ile Asn Ala Leu Pro Ala Ile Ala Leu Ile Asn Tyr Gly Phe 195 200 205 Ser Asn Glu Gly Leu Leu Pro Gly Ala Cys Phe Gly Val Gly Leu Gly 210 215 220 Thr Thr Val Cys Gly Met Ala Tyr Ile Phe Leu His Asn Gly Leu Ser 225 230 235 240 His Arg Arg Phe Pro Val Trp Leu Ile Ala Asn Val Pro Tyr Phe His 245 250 255 Lys Leu Ala Ala Ala His Gln Ile His His Ser Gly Lys Phe Gln Gly 260 265 270 Val Pro Phe Gly Leu Phe Leu Gly Pro Lys Glu Leu Glu Glu Val Arg 275 280 285 Gly Gly Thr Glu Glu Leu Glu Arg Val Ile Ser Arg Thr Thr Lys Arg 290 295 300 Thr Gln Pro Ser Thr 305 13 310 PRT Arabidopsis misc_feature (4)..(4) “Xaa” is any amino acid 13 Met Ala Ala Xaa Leu Ser Thr Ala Val Thr Phe Lys Pro Leu His Arg 1 5 10 15 Ser Phe Ser Ser Ser Ser Thr Asp Phe Arg Leu Arg Leu Pro Lys Ser 20 25 30 Leu Ser Gly Phe Ser Pro Ser Leu Arg Phe Lys Arg Phe Ser Val Cys 35 40 45 Tyr Val Val Glu Glu Arg Arg Gln Asn Ser Pro Ile Glu Asn Asp Glu 50 55 60 Arg Pro Glu Ser Thr Ser Ser Thr Asn Ala Ile Asp Ala Glu Tyr Leu 65 70 75 80 Ala Leu Arg Leu Ala Glu Lys Leu Glu Arg Lys Lys Ser Glu Arg Ser 85 90 95 Thr Tyr Leu Ile Ala Ala Met Leu Ser Ser Phe Gly Ile Thr Ser Met 100 105 110 Ala Val Met Ala Val Tyr Tyr Arg Phe Ser Trp Gln Met Glu Gly Gly 115 120 125 Glu Ile Ser Met Leu Glu Met Phe Gly Thr Phe Ala Leu Ser Val Gly 130 135 140 Ala Ala Val Gly Met Glu Phe Trp Ala Arg Trp Ala His Arg Ala Leu 145 150 155 160 Trp His Ala Ser Leu Trp Asn Met His Glu Ser His His Lys Pro Arg 165 170 175 Glu Gly Pro Phe Glu Leu Asn Asp Val Phe Ala Ile Val Asn Ala Gly 180 185 190 Pro Ala Ile Gly Leu Leu Ser Tyr Gly Phe Phe Asn Lys Gly Leu Val 195 200 205 Pro Gly Leu Cys Phe Gly Ala Gly Leu Gly Ile Thr Val Phe Gly Ile 210 215 220 Ala Tyr Met Phe Val His Asp Gly Leu Val His Lys Arg Phe Pro Val 225 230 235 240 Gly Pro Ile Ala Asp Val Pro Tyr Leu Arg Lys Val Ala Ala Ala His 245 250 255 Gln Leu His His Thr Asp Lys Phe Asn Gly Val Pro Tyr Gly Leu Phe 260 265 270 Leu Gly Pro Lys Glu Leu Glu Glu Val Gly Gly Asn Glu Glu Leu Asp 275 280 285 Lys Glu Ile Ser Arg Arg Ile Lys Ser Tyr Lys Lys Ala Ser Gly Ser 290 295 300 Gly Ser Ser Ser Ser Ser 305 310 14 305 PRT Arabidopsis 14 Met Ala Ala Gly Leu Ser Thr Ile Ala Val Thr Leu Lys Pro Leu Asn 1 5 10 15 Arg Ser Ser Phe Ser Ala Asn His Pro Ile Ser Thr Ala Val Phe Pro 20 25 30 Pro Ser Leu Arg Phe Asn Gly Phe Arg Arg Arg Lys Ile Leu Thr Val 35 40 45 Cys Phe Val Val Glu Glu Arg Lys Gln Ser Ser Pro Met Asp Asp Asp 50 55 60 Asn Lys Pro Glu Ser Thr Thr Ser Ser Ser Glu Ile Leu Met Thr Ser 65 70 75 80 Arg Leu Leu Lys Lys Ala Glu Lys Lys Lys Ser Glu Arg Phe Thr Tyr 85 90 95 Leu Ile Ala Ala Val Met Ser Ser Phe Gly Ile Thr Ser Met Ala Ile 100 105 110 Met Ala Val Tyr Tyr Arg Phe Ser Trp Gln Met Lys Gly Gly Glu Val 115 120 125 Ser Val Leu Glu Met Phe Gly Thr Phe Ala Leu Ser Val Gly Ala Ala 130 135 140 Val Val Gly Met Glu Phe Trp Ala Arg Trp Ala His Arg Ala Leu Trp 145 150 155 160 His Asp Ser Leu Trp Asn Met His Glu Ser His His Lys Pro Arg Glu 165 170 175 Gly Ala Phe Glu Leu Asn Asp Val Phe Ala Ile Thr Asn Ala Val Pro 180 185 190 Ala Ile Gly Leu Leu Tyr Tyr Gly Phe Leu Asn Lys Gly Leu Val Pro 195 200 205 Gly Leu Cys Phe Gly Ala Gly Leu Gly Ile Thr Met Phe Gly Met Ala 210 215 220 Tyr Met Phe Val His Asp Gly Leu Val His Lys Arg Phe Pro Val Gly 225 230 235 240 Pro Ile Ala Asn Val Pro Tyr Leu Arg Lys Val Ala Ala Ala His Gln 245 250 255 Leu His His Thr Asp Lys Phe Lys Gly Val Pro Tyr Gly Leu Phe Leu 260 265 270 Gly Pro Lys Gln Glu Val Glu Glu Val Gly Gly Lys Glu Glu Leu Glu 275 280 285 Lys Glu Ile Ser Arg Arg Ile Lys Leu Tyr Asn Lys Gly Ser Ser Thr 290 295 300 Ser 305 15 315 PRT Capsicum annuum 15 Met Ala Ala Glu Ile Ser Ile Ser Ala Ser Ser Arg Ala Ile Cys Leu 1 5 10 15 Gln Arg Asn Pro Phe Pro Ala Pro Lys Tyr Phe Ala Thr Ala Pro Pro 20 25 30 Leu Leu Phe Phe Ser Pro Leu Thr Cys Asn Leu Asp Ala Ile Leu Arg 35 40 45 Ser Arg Arg Lys Pro Arg Leu Ala Ala Cys Phe Val Leu Lys Asp Asp 50 55 60 Lys Leu Tyr Thr Ala Gln Ser Gly Lys Gln Ser Asp Thr Glu Ala Ile 65 70 75 80 Gly Asp Glu Ile Glu Val Glu Thr Asn Glu Glu Lys Ser Leu Ala Val 85 90 95 Arg Leu Ala Glu Lys Phe Ala Arg Lys Lys Ser Glu Arg Phe Thr Tyr 100 105 110 Leu Val Ala Ala Val Met Ser Ser Leu Gly Ile Thr Ser Met Ala Val 115 120 125 Ile Ser Val Tyr Tyr Arg Phe Ser Trp Gln Met Glu Gly Gly Glu Met 130 135 140 Pro Phe Ser Glu Met Phe Cys Thr Phe Ala Leu Ala Phe Gly Ala Ala 145 150 155 160 Ile Gly Met Glu Tyr Trp Ala Arg Trp Ala His Arg Ala Leu Trp His 165 170 175 Ala Ser Leu Trp His Met His Glu Ser His His Arg Pro Arg Glu Gly 180 185 190 Pro Phe Glu Leu Asn Asp Ile Phe Ala Ile Ile Asn Ala Val Pro Ala 195 200 205 Ile Ala Phe Phe Ser Phe Gly Phe Asn His Lys Gly Leu Ile Pro Gly 210 215 220 Ile Cys Phe Gly Ala Gly Leu Gly Ile Thr Val Phe Gly Met Ala Tyr 225 230 235 240 Met Phe Val His Asp Gly Leu Val His Lys Arg Phe Pro Val Gly Pro 245 250 255 Ile Ala Lys Val Pro Tyr Phe Gln Arg Val Ala Ala Ala His Gln Leu 260 265 270 His His Ser Asp Lys Phe Asp Gly Val Pro Tyr Gly Leu Phe Leu Gly 275 280 285 Pro Lys Glu Leu Glu Glu Val Gly Val Ile Glu Glu Leu Glu Lys Glu 290 295 300 Val Asn Arg Arg Ile Lys Ser Leu Lys Arg Leu 305 310 315 16 316 PRT Capsicum annuum 16 Thr Thr Gly Arg Tyr His Tyr Gln Leu Val Trp Cys Gln Ile Ser Phe 1 5 10 15 Ser Ser Thr Ser Arg Thr Ser Tyr Tyr Arg His Ser Pro Phe Leu Gly 20 25 30 Pro Lys Pro Thr Pro Thr Thr Pro Ser Val Tyr Pro Ile Thr Pro Phe 35 40 45 Ser Pro Asn Leu Gly Ser Ile Leu Arg Cys Arg Arg Arg Pro Ser Phe 50 55 60 Thr Val Cys Phe Val Leu Glu Asp Asp Lys Phe Lys Thr Gln Phe Glu 65 70 75 80 Ala Gly Glu Glu Asp Ile Glu Met Lys Ile Glu Glu Gln Ile Ser Ala 85 90 95 Thr Arg Leu Ala Glu Lys Leu Ala Arg Lys Lys Ser Glu Arg Phe Thr 100 105 110 Tyr Leu Val Ala Ala Val Met Ser Ser Phe Gly Ile Thr Ser Met Ala 115 120 125 Val Met Ala Val Tyr Tyr Arg Phe Tyr Trp Gln Met Glu Gly Gly Glu 130 135 140 Val Pro Phe Ser Glu Met Phe Gly Thr Phe Ala Leu Ser Val Gly Ala 145 150 155 160 Ala Val Gly Met Glu Phe Trp Ala Arg Trp Ala His Lys Ala Leu Trp 165 170 175 His Ala Ser Leu Trp His Met His Glu Ser His His Lys Pro Arg Glu 180 185 190 Gly Pro Phe Glu Leu Asn Asp Val Phe Ala Ile Ile Asn Ala Val Pro 195 200 205 Ala Ile Ala Leu Leu Asp Tyr Gly Phe Phe His Lys Gly Leu Ile Pro 210 215 220 Gly Leu Cys Phe Gly Ala Gly Leu Gly Ile Thr Val Phe Gly Met Ala 225 230 235 240 Tyr Met Phe Val His Asp Gly Leu Val His Lys Arg Phe Pro Val Gly 245 250 255 Pro Val Ala Asn Val Pro Tyr Leu Arg Lys Val Ala Ala Ala His Ser 260 265 270 Leu His His Ser Glu Lys Phe Asn Gly Val Pro Tyr Gly Leu Phe Leu 275 280 285 Gly Pro Lys Glu Leu Glu Glu Val Gly Gly Leu Glu Glu Leu Glu Lys 290 295 300 Glu Val Asn Arg Arg Thr Arg Tyr Ile Lys Gly Ser 305 310 315 17 29 DNA Artificial Sequence Description of Artificial Sequence Synthetic 17 cagaatcggt ctgttctatt agttcttcc 29 18 32 DNA Artificial Sequence Description of Artificial Sequence Synthetic 18 caatttgagg aatatcaagg ttccttgttc tc 32 

I claim:
 1. A method of producing a ketocarotenoid in a host cell, the method comprising inserting into the host cell a vector comprising a heterologous nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has the nucleic acid sequence of SEQ ID NO: 1 or 3, wherein the heterologous nucleic acid sequence is operably linked to a promoter; and expressing the heterologous nucleic acid sequence, thereby producing the ketocarotenoid.
 2. The method of claim 1, wherein the host cell is selected from the group consisting of a bacterial cell, an algal cell and a plant cell.
 3. A method of producing a ketocarotenoid in a host cell, the method comprising inserting into the host cell a vector comprising a heterologous nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has a sequence which encodes the amino acid sequence of SEQ ID NO: 2 or 4, wherein the heterologous nucleic acid sequence is operably linked to a promoter; and expressing the heterologous nucleic acid sequence, thereby producing the ketocarotenoid.
 4. The method of claim 3, wherein the host cell is selected from the group consisting of a bacterial cell, an algal cell and a plant cell.
 5. A method of modifying the production of carotenoids in a host cell, relative to an untransformed host cell, the method comprising inserting into a host cell which already produces carotenoids a vector comprising a heterologous nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has the nucleic acid sequence of SEQ ID NO: 1 or 3, wherein the heterologous nucleic acid sequence is operably linked to a promoter; and expressing the heterologous nucleic acid sequence in the host cell to modify the production of the carotenoids in the host cell, relative to an untransformed host cell.
 6. The method of claim 5, wherein the host cell is selected from the group consisting of a bacterial cell, an algal cell and a plant cell.
 7. A method of modifying the production of carotenoids in a host cell, relative to an untransformed host cell, the method comprising inserting into a host cell which already produces carotenoids a vector comprising a heterologous nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has a sequence which encodes the amino acid sequence of SEQ ID NO: 2 or 4, wherein the heterologous nucleic acid sequence is operably linked to a promoter; and expressing the heterologous nucleic acid sequence in the host cell to modify the production of the carotenoids in the host cell, relative to an untransformed host cell.
 8. The method of claim 7, wherein the host cell is selected from the group consisting of a bacterial cell, an algal cell and a plant cell.
 9. A purified nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has the nucleic acid sequence of SEQ ID NO:
 1. 10. A purified nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has the nucleic acid sequence of SEQ ID NO:
 3. 11. A purified nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has a sequence which encodes the amino acid sequence of SEQ ID NO:
 2. 12. A purified nucleic acid sequence which encodes for a protein having ketolase enzyme activity and has a sequence which encodes the amino acid sequence of SEQ ID NO:
 4. 13. A vector which comprises the nucleic acid sequence of any one of claims 9-12, wherein the nucleic acid sequence is operably linked to a promoter.
 14. A host cell which is transformed with the vector of claim
 13. 15. The host cell of claim 14, wherein the host cell is selected from the group consisting of a bacterial cell, an algal cell and a plant cell.
 16. The host cell of claim 14, wherein the host cell is a photosynthetic cell.
 17. The host cell of claim 14, wherein the host cell contains a ketocarotenoid.
 18. The host cell of claim 14, wherein the host cell contains modified levels of carotenoids, relative to an untransformed host cell.
 19. A purified ketolase enzyme comprising the amino acid sequence of SEQ ID NO:
 2. 20. A purified ketolase enzyme comprising the amino acid sequence of SEQ ID NO:
 4. 